Author: admin

Lathe chuck

The lathe-project I bought in November is slowly moving forward. I got an Optimum/Quantum 100mm 3-jaw chuck for it today. Turns out the spindle needs to be disassembled to attach the chuck, so this was an opportunity to look at how the spindle is built.

The front bearing seat is machined into the spindle box, while the back bearing seat is a separate bolted on part. The front bearing has a nice 2-part aluminium chip-guard which protects the bearing from coolant and chips. A chip/dust-guard for the back bearing would probably be a good idea too. The spindle is held in place with a nut against the back bearing that tightens the whole assembly. This nut will probably need a set-screw or something else to secure it rigidly (rapid accelerations, changes of direction etc. might otherwise loosen it?). The chuck attaches with three M8 hex bolts, and the 20mm ones which came with the chuck are a bit short - need to buy 3pcs 25mm M8 hex bolts. For now everything is dripping with anti-corrosion spray, but for use the bearings will require either grease or oil (oil is better for higher RPM?). Also, I need to source a timing-belt and 1:1 pulleys to transmit ca 2kW @ 3000-3500RPM from the spindle-servo up to the spindle. Any suggestions?

2:12:56 Helsinki City Run

Despite forecasts of rain during the week the weather cooperated nicely and we only got wet after 18 km or so.

At about 14 km my legs started to feel heavy, and after the last gatorade+water station at 17 km I started walking all the uphills.

I finished in 6345th place (yay!) out of 13100 runners, and the timing-chip time was 2:12:56, my own garmin said 2:12:59, and my official time (start-gun to finish) was 2:13:16.

Results and info here: http://www.helsinkicityrun.fi

Links - 2010 May 6

CNC-turned stainless steel IOM bulb

CNC-turned from stainless steel, this is a 400mm long and 38mm diameter IOM keel bulb. A slot will be milled in the middle for the keel fin. Unlike a lead-bulb this one will require no surface filler/sanding/painting. But the density (compared to water) of stainless steel is 8 at most, while lead bulbs can be close to 11 (depending on the lead-alloy), which means the volume of this bulb is slightly larger.

Sunday seventeen

The books seem to tell me that to gain endurance you don't have to run fast, and often recommend a pace 90s to 2min/mile slower than race-pace for long runs. That's around 6:30 to 7min/km pace if race-pace is a 4h marathon. My avg. pace was 6:48/km today at avg. HR 154. A recovery jog on Monday or Tuesday, and then a faster 5k on Wednesday or Thursday - that should be about the final prep for the half-marathon next Saturday.

This scenic loop is close to what they use for part of the Helsinki City Marathon (2009 map here).

Composite cutters for ocl

People who, unlike me, actually know something about programming often talk about design patterns. One common idea is to compose objects out of other objects.

I was able to add four new APT-tool like cutter classes to ocl with about 5-lines of code for each cutter (sans the bugfixing, taking much longer, that also took place simultaneously 🙂 ).

These show CL-points resulting from the vertexDrop() function, which results in a shape that looks like the cutter, but inverted.

Other combinations of the basic shapes (cylinder, sphere, torus, cone) are fairly easy to add now also if someone actually needs them.

Thursday eleven

This pace is slightly slower than a 2 hour half-marathon, but that is partly because of the traffic-lights and other obstacles in the course. Kilometers 9, 10, and 11 felt pretty good - I wonder how much beyond 11k the wall lies?

In other news, lucid lynx is out, and my desktop machine is taking forever to download about 2600 Mb of upgrades.

Links - 2010 Apr 29

Tuesday 5k

The GPS has serious problems on "Nokia avenue" in between high buildings...

Legs still feel a bit heavy from 10k on Saturday. Pace is 4h marathon pace, or around 5:32 to 5:40min/km.

Model Expo Sunday

Some random pics from Sunday at the 2010 Helsinki Model Expo.

The two 1:10RC scale yachts look nice, but must take an enormous amount of time to build, and are 140cm long and weigh 10kg (like a 1970-80s Marblehead?). All of which contrasts quite strongly with the MicroMagic, where presumably some of the better sailing this season will take place. We had one PIKANTO hull and some components on display, but we really don't have a handle on producing these hulls or parts at a rate or cost that would make it possible to sell or market them (yet?).

Some lathes, and a miniature Proxxon machine-park, on display. But nothing running EMC2 or the size/speed/awasomeness that would have raised my interest further. If I finish the lathe this summer I think something like a hexapod must be next on the todo-list...

1090 euros (about 1450 USD!) seems a bit steep for a MakerBot CupCake kit, which seems to cost about 750-950 USD elsewhere (googling gets me here or here or review-here). Unfortunately this kind of pricing is quite common with companies that import stuff. I won't miss these companies when they go out of business because everyone (sane) orders directly from Germany/USA/China/etc.

In a normal BLDC motor the windings are stationary on the outside, and a permanent-magnet rotor in the middle rotates. On outrunners this is reversed: the windings are stationary in the middle, and a rotor with permanent magnets is on the outside. The pictures here and here show a DIY electric motor I had not seen before. Both the windings and the permanent magnets rotate, in opposite directions. They are coupled to two propellers which rotate in opposite directions, and it apparently works quite well!